Senate lawmakers investigating Russian interference in the 2016 presidential race warned on Wednesday that the United States remains susceptible to further election meddling and misinformation campaigns.
In doing so, though, the leaders of the Senate Intelligence Committee — Republican Chairman Richard Burr and ranking Democratic Sen. Mark Warner — stressed at a joint press conference that they have many unresolved questions for Facebook, Google and Twitter, and they urged executives to testify at a hearing scheduled for November 1.
“The Russian intelligence service is determined, clever, and I recommend every campaign and every election official take this very seriously as we move into this November’s election,” Burr said.
The contest Burr referenced actually happens next month in Virginia, the state that his colleague, Warner, represents. “The Russian active measures did not end on Election Day 2016,” Warner affirmed.
For tech giants, meanwhile, the Senate’s chief investigators once again sounded alarms about the extent to which Russian forces purchased ads and created false accounts “that would drive interest toward stories or groups,” with the goal to “sow chaos and drive division in our country,” Warner said.
Neither Warner nor Burr addressed whether those accounts and advertisements are explicitly tied to the Trump campaign, and the committee made clear it would not be releasing copies of the information it’s obtained from tech giants. But, Warner emphasized: “We think it’s important the three companies we invited, Google, Twitter and Facebook, will appear in a public hearing.”
Spokespeople for Facebook, Google and Twitter did not immediately respond to emails seeking comment on Wednesday.
So far, Facebook has uncovered roughly 470 profiles tied to Russian-backed sources. Those profiles purchased about 3,000 ads, now in lawmakers’ possession, which sought to stoke political unrest in the United States. Facebook estimates that approximately 10 million users in the United States saw the ads before and after Election Day.
Twitter, meanwhile, has found about 200 accounts with suspicious Russian ties. Google has not released any information about Kremlin activities on its advertising platform or other websites, like YouTube, though an investigation is ongoing. Snap has evaluated its platforms for potential misuse — and so far, it’s found nothing. And companies including Oath, formerly Yahoo, and Reddit, have provided scant details as to whether they’ve conducted internal investigations, or what they may have found.
In recent weeks, these tech companies have promised to harden their defenses against future election meddling. Facebook, for example, pledged 1,000 new hires devoted to monitoring ads and greater investments in machine-learning technology. And Twitter said it’s reviewing its own practices to prevent such disinformation campaigns from happening again.
At first, lawmakers lambasted the whole of Silicon Valley for failing to do more, and sooner, to combat Russia and other malefactors. Warner and others specifically have singled out Twitter for failing to perform an exhaustive search of its sales records for ads and accounts used by Kremlin agents.
On Wednesday, however, Warner seemed to moderate his town. He acknowledged that tech companies had come to understand the seriousness of the threats facing social media sites -- and American voters. But the senator repeated his belief that there is still a great deal for Facebook, Google and Twitter to address to satisfy users and congressional investigators alike. That includes greater disclosure for ads so that “Americans can know if the source of that ad was generated by foreign entities,” he said at the press conference.
To that end, Warner and one of his Democratic colleagues, Sen. Amy Klobuchar, are expected to introduce new political transparency legislation in the coming days. The measure could require tech companies selling political ads to keep and publish copies of them for viewers to see. That would mimic a system already in place for similar political content that runs on television. So far, though, the proposal does not appear to have any Republican sponsors.
In the House, meanwhile, the chamber’s own intelligence committee is conducting a parallel probe of potential Russian interference in the 2016 presidential election. That panel aims to hold its own hearing with Facebook, Google and Twitter in October, though it has not officially been scheduled.
This article originally appeared on Recode.net.